The present invention relates to the field of treating prostate cancer which, at the present time, is based on several therapeutic routes dependent on the degree of progress of the disease. The hormonal treatment of metastatic prostate cancer which has crossed the capsule currently relies mainly on several categories of medicinal products which act at different levels on the hypothalamo-gonad axis.
The efficacy and limits of hormonal treatments are now more or less defined. These limits are set both by the side effects, in particular vascular effects for estrogens at high doses, and sexual, gastric and pulmonary effects for antiandrogens, and by the emergence of immediate or secondary resistance.
The current attitude appears to be focused, at least at the initial phase of the treatment, on total androgenic blockage (inhibition of the testicular secretion of androgens and inhibition of the activity of the residual androgens on the target organ). Specifically, the absence of absolute certainty regarding the advantage of continuing this combination long term occasionally results in a complete androgenic blockage being preferred at the time of starting a treatment with an LHRH agonist, in order to prevent initial flare-ups with subsequent continuation of the agonist alone.
The prognosis for developed prostate cancers and the androgen dependence of many of them is encouragement for eradicating as fully as possible the androgenic environment, including the adrenal environment. The superiority of a long-term combined treatment (surgical castration or LHRH agonist combined with an antiandrogen therapy) on the life expectancy is more and more confirmed.
Irrespective of the initial hormonal treatment applied, the response barely goes beyond two years up to the installation of the hormone resistance phase. Neither a change in hormone therapy nor the use of chemotherapy has hitherto made it possible to prolong significantly the median survival time, which remains about eighteen months.
Hormone therapy, with the aim of eliminating the hormones responsible for the tumor growth, generally involves the administration of LHRH agonists alone or combined with antiandrogen agents (see for example patent FR 2 465 486).
Cancerous prostate cells may also be partially eliminated by radiotherapy and/or by surgical intervention.
For the treatment of prostate cancer, a practitioner therefore currently has several means of intervention at his disposal. Mention will be made firstly of surgery, then of LHRH analogs, and finally of antiandrogens used either in combination with medical or surgical castration or in monotherapy, and finally radiotherapy.
However, none of these means is considered entirely satisfactory at the present time. Although it is known that hormone sensitivity justifies the use of hormone therapy, the studies conducted to date do not enable the optimum modes of the benefit/risk ratio to be defined precisely.
Specifically, chemical castration leads to impotence and a reduction in libido, this effect possibly being reversible on stopping the treatment, but with a risk of more or less long-term relapse.
The present invention constitutes a decisive improvement in the treatment of prostate cancer. The invention is directed more particularly toward the use of a lipid-sterol extract of Serenoa repens to manufacture a medicinal product to be administered individually or in combination, simultaneously, separately or sequentially over time, with a prostatectomy, radiotherapy and/or a hormone therapy, for the treatment or prevention of prostate cancer.
In the context of the present invention, it has been observed that the lipid-sterol extract of Serenoa Repens plays a role in inducing apoptosis, allowing the first line treatment before surgery or radiotherapy, in order to avoid the dissemination of the tumor outside the prostate capsule.
In addition, the lipid-sterol extract of Serenoa Repens combined with a hormonal treatment makes it possible, on stopping the hormonal treatment, to control the tumor progression by inducing cell death. Such a sequential treatment enables the benefit/risk ratio to be improved considerably.
Finally, after prostatectomy and/or after radiotherapy, the lipid-sterol extract of Serenoa Repens retards the progression of cancer cells which might have escaped treatment.
To illustrate the hormone therapy treatment combined with the administration of the lipid-sterol extract of Serenoa Repens according to the invention, mention will be made firstly of LHRH agonists or antagonists, in particular triptorelin, leuprorelin, nafarelin, goserelinor or buserelin and also nonsteroidal antiandrogens such as flutamide, nilutamide or bicalutamide.
According to one advantageous variant of the present invention, said medicinal product is administered in combination with an antiandrogen combined with an LHRH agonist or antagonist.
The lipid-sterol extract of Serenoa Repens has been used hitherto for treating benign hyperplasia of the prostate. In the context of the present invention, it has been found, unexpectedly, that the lipid-sterol extract of Serenoa Repens can in fact act as an apoptosis inducer for prostate epithelial and stromal cells.
Following these observations, several clinical trials were conducted, which have made it possible to site the advantage of the lipid-sterol extract of Serenoa Repens among the therapeutic arsenal used for treating prostate cancer.
It should be recalled that the lipid-sterol extract of Serenoa Repens is an assayed extract obtained from Serenoa Repens (Sabal Serrulata, Saw Palmeto).
This extract is obtained more particularly using hydrophobic solvents such as supercritical CO2 or hexane. Such an extract contains no phytoestrogens, which differentiates it from soya isoflavones or from any other phytoestrogens as described, for example, in New England J. of Medicine Vol. 339 (12) pp. 785-791.
This extract may be assayed as free fatty acids (lauric acid+oleic acid=65%) and as fatty alcohols which are traces of the unsaponifiable portion (0.2%). For a more complete description of the process for manufacturing such an extract, reference may be made, for example, to the description of patent FR 2 480 754.